Method for marking gemstones with a unique micro discrete indicia

ABSTRACT

A method for providing and reading micro-discrete indicia on a gemstone using near-field optics.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a divisional of application Ser. No. 10/027,016, filedDec. 21, 2001, entitled METHOD FOR MARKING GEMSTONES WITH A UNIQUE MICRODISCRETE INDICIA, in the names of David L. Patton, et al.

[0002] Reference is made to commonly assigned, copending applicationsU.S. Serial No. [Attorney Docket 83,891AF-P] entitled METHOD FOR MARKINGGEMSTONES WITH A UNIQUE MICRO DISCRETE INDICIA, in the names of David L.Patton, et al filed concurrently herewith.

FIELD OF THE INVENTION

[0003] This invention relates a method and system for forming uniquemicro discrete indicia on a gemstone such as a diamond using near-fieldoptical imaging.

BACKGROUND OF THE INVENTION

[0004] Recent advances in optics provide for a method of exposure ofmaterials on a length scale much smaller than previously realized. Suchnear-field optical methods are realized by placing an aperture or a lensin close proximity to the surface of the sample or material to beexposed. Special methods for positioning control of the aperture or lensare required, as the distance between the optical elements (aperture orlens) is extremely small. Betzig and Trautman in U.S. Pat. No. 5,272,330reported on the use of tapered optical fibers as a means of providingexposures in extremely small areas; exposures of the size of 10 nm inarea are now relatively commonplace. In this case, the fiber tipposition is maintained to be within some nanometers (typically 10-50) ofthe target surface. Others (see, for example, the review by Q. Wu, L.Ghislain, and V. B. Elings, Proc. IEEE (2000), 88(9), pg. 1491-1498)have developed means of exposure by the use of the solid immersion lens(SIL). Exposures produced by means of the SIL or other near-fieldoptical methods can be much smaller in spatial extent than thoseproduced by conventional optical systems and still be readable.

[0005] Optical means to mark diamonds and other gemstones have beenpreviously described. Kaplan et al. in U.S. Pat. No. 6,211,484 B1describe the use of a pulsed laser system and precision mechanicalpositioning controls to mark gemstones and a process to produce a securecertificate of authenticity. The laser in this instance operates with anapproximate wavelength of 530 nanometers. This system achieves apositioning accuracy of about plus or minus a micron. The laser exposureproduces a series of ablated or graphitic spots on the gemstone surface.

[0006] Smith et al. in U.S. Pat. No. 6,187,213 B1 describe the use of anultraviolet (UV) laser system for marking diamond. The use of the 193nanometers exposure with conventional optical elements produces a markthat is invisible because of its small size when viewed using an ×10loupe.

[0007] In U.S. Pat. No. 5,753,887, Rosenwasser et al. describe the useof a laser system for engraving indicia on gemstones. Their inventionentails the use of a gemstone holding system that minimizes internalexposure and thus damage to the internal structure of the gemstone. Thisminimization is accomplished by use of light transmissive elements tohold and position the gemstone. Such minimization is especiallyimportant in the application of novelty marking of larger gemstoneswhere some considerable optical exposure is required in order to markthe gemstone.

[0008] The prior art does not teach marking a gemstone using near-fieldoptics. Such near-field technology is used in the present invention toprovide a means of marking a gemstone with micro discrete indicia and touse these micro discrete indicia for the purpose of authentication andpersonalization. The size of the micro discrete indicia produced usingnear-field technology is such that they do detract from the physicalappearance of the gemstone.

[0009] The prior art does not teach the forming of the micro discreteindicia on a gemstone using near-field optics to alter the color ofgemstone materials.

[0010] The prior art also does not teach linking the micro discreteindicia produced using near-field optics to an owner, retailer, orproducer via a database for the purpose of authentication.

SUMMARY OF THE INVENTION

[0011] In accordance with one aspect of the present invention there isprovided a gemstone having a micro-discrete indicia formed thereonwherein said micro-discrete indicia image was formed using near-fieldoptics.

[0012] This and other aspects, objects, features, and advantages of thepresent invention will be more clearly understood and appreciated from areview of the following detailed description of the preferredembodiments and appended claims, and by reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In the detailed description of the preferred embodiments of theinvention presented below, reference is made to the accompanyingdrawings in which:

[0014]FIG. 1 is a schematic view of an apparatus for forming the variousindicia on a gemstone using near-field optics;

[0015]FIGS. 2a, b, and c are schematics illustrating different surfaceson a gemstone, onto which the indicia may be formed using near-fieldoptics;

[0016]FIG. 3 is an enlarged plan view of a gemstone made in accordancewith the present invention containing unique micro discrete indicia;

[0017]FIG. 4 is an enlarged partial view of a portion of the gemstone ofFIG. 3 illustrating micro discrete indicia;

[0018]FIG. 5 is a schematic view of another embodiment the apparatus forforming the various indicia on a gemstone using near-field optics madein accordance with the present invention;

[0019]FIG. 6 is a schematic view of yet another embodiment the apparatusfor forming the various indicia on a gemstone using near-field opticsmade in accordance with the present invention;

[0020]FIG. 7a is a schematic illustrating a method for locating theindicia on a gemstone described in FIG. 4 made in accordance with thepresent invention;

[0021]FIG. 7b is an enlarged partial view of a portion of the gemstoneof FIG. 7a where the indicia are provided;

[0022]FIG. 8 is a schematic view of an apparatus used for viewing themicro discrete indicia located on the gemstone described in FIG. 4; and

[0023]FIG. 9 is an enlarged partial view of the image of the microdiscrete indicia located on the gemstone displayed by the apparatusdescribed in FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

[0024] The invention has been described in detail with particularreference to certain preferred embodiments thereof, but it will beunderstood that variations and modifications can be effected within thespirit and scope of the invention.

[0025] Because of their high value, diamonds and other gemstones arefrequently marked for purposes of authentication. Additionally, diamondsand other gemstones are marked for personalization, decorative, ornovelty reasons. It is important that such markings do not detract fromthe appearance of the finished diamond or gemstone. In theauthentication of such gemstones, indicia or other markings should notbe visible to the purchaser under ordinary use conditions so as topreclude detracting from the finished appearance. For purposes ofpersonalization, novelty, or decoration, such markings should be madewith extreme precision, while the desirability for making such markingsvisible under ordinary use conditions may or may not be a requirement.In either of these situations, the use of near-field optical methods formarking is advantageous since the resolution is higher than conventionalmeans of optical exposure. This enables either a more precise exposureor the production of indicia that are smaller than that produced byconventional means of optical exposure. The invention provides a methodand system for marking each gemstone with a unique identification numberthat is recorded in a data record so it can be used to track theheritage and ownership of the gemstone. The unique identification numbercan be assigned or registered to an owner, retailer, producer, countryof origin, mine, etc.

[0026] The method comprises a system for the creation of unique microdiscrete indicia on a gemstone using near-field optics the gemstone maybe a diamond, ruby, sapphire, emerald, opal etc. The micro discreteindicia can be an alphanumeric, a logo, a symbol, a design, etc. Thesize of each micro discrete indicium is in the range of 2 to 20 microns.The method of identifying the gemstone using the unique micro discreteindicia includes locating and scanning or optically viewing the gemstoneand viewing the micro discrete indicia. The obtained micro discreteindicia may be used for a variety of purposes. For example, theidentification indicia can be used to identify a particular gemstone onwhich it is formed. Alternatively, the micro discrete indicia is wellsuited for authentication of the gemstone. For example, the gemstone isgenuine and/or comes from a particular source. Finally, the method maybe used for purposes of personalization, ornamentation, decorative, ornovelty reasons.

[0027] Referring now to FIG. 1, there is illustrated an apparatus 10 forforming unique micro discrete indicia 15 on a gemstone 20 such as adiamond. Indicia 15 are created on the gemstone 20 by transmitting lightfrom a light source 45 through a mask 25 containing an image 27. Thelight beam 40 from a variety of laser light sources 45 such as anExcimer, or a frequency doubled Nd:YAG laser passes through the mask 27and is reflected by a mirror 50, through a lens system 55 and passesthrough an objective lens 66 of conventional design and impinges onto asolid immersion lens (SIL) 65. The gemstone 20 resting on a stage 70 isplaced within a critical distance f. Images formed from such a systemwill have a lateral spatial resolution that exceeds the classicaldiffraction limit as is well known to those skilled in the art. Thelight beam 75 passes through an objective lens 60 of conventional designand impinges onto a solid immersion lens (SIL) 65. The SIL 65 ispositioned within the near-field coupling limit appropriate for theparticular lens in use by the use of a positioning device 80. U.S. Pat.No. 5,121,256, Corle et al. discloses a method for positioning an SILusing an interferometer constructed between the SIL and the sample. Alaser can be used to set up standing waves between the bottom surface ofthe SIL and the top surface of the sample. In one configuration thelaser can be brought into the system through a beam splitter in such away as to produce plane waves in the region between the bottom of theSIL and the top of the sample. There will be interference between thelaser light reflected from the bottom of the SIL and the top of thesample. A path difference of a quarter of a wavelength (λ/4) will causethe interference pattern to change from bright to dark so thatcontrolling the distance between the SIL and the sample to a fewnanometers is achieved by sensing the reflected light with a photodiodeor the like and using the output as the input to a control system. Anumber of physical mechanisms play a role in the marking of a diamond orgemstone. Included among these is light-induced ablation of the gemstonematerial as a result of the rapid deposition of energy from the laserlight beam. In some instances a light absorbing material is coated onthe diamond or gemstone surface to facilitate direct absorption of thelight beam energy. Subsequent conversion of the absorbed energy to heatcauses material to be ablated from the near-surface region. Coloredgemstones in most instances do not require this surface coating to beapplied. It is also possible to alter the color of gemstone materials asa result of the laser light beam affecting the defect concentration inthe gemstone or diamond material. It is known to those skilled in thedefect physics of such materials that either through direct lightabsorption into existing defect optical absorption bands or throughmulti-photon absorption processes, color center can be produced in thesematerials. The presence of these color centers as a result of the actionof the laser light write beam can be determined by a variety of opticalmethods including absorption or luminescence measurement. The stage 70is located on an x, y, z, and θ translation device 90. Alternativelythere are many other known translation devices for positioning the stage70 in the art such as nano or micro positioning techniques. The image 27used to form the micro discrete indicia 15 can be an alphanumeric or asymbol such as a logo. If an alphanumeric is used as the micro image,this can also be used as a serial number and/or code for use in furtherauthenticating the gemstone or providing additional information directlyfrom the alphanumeric or be used to look up information from a database.

[0028] Referring to FIGS. 2a, b, and c, there are illustrated thedifferent surfaces on which the indicia may be formed using near-fieldoptics.

[0029] Referring to FIG. 3, there is illustrated a plan view of thegemstone containing the micro discrete indicia 15 shown in an enlargedplan view in FIG. 4. Preferably the length “d” of the indicia 15 is nogreater than approximately 10 microns and a height “h” is no greaterthan approximately 2 microns. The indicia 20 can be of such a size thatcan be read using near-field optical imaging when placed on the gemstonebut not detract from the original appearance as viewed under normalviewing conditions.

[0030] Referring now to FIG. 5, there is illustrated another embodimentof the apparatus for forming the various indicia on a gemstone usingnear-field optics made in accordance with the present invention. Indicia15 are created on the gemstone 20 by transmitting light from a laser100. The laser light beam 110 is reflected by a mirror 105, through alens system 55 and passes through an objective lens 60 of conventionaldesign and impinges onto a solid immersion lens (SIL) 65. The gemstone20 resting on a stage 70 is placed within a critical distance f. The SIL65 is positioned within the near-field coupling limit appropriate forthe particular lens in use by the use of a positioning device 80. Such apositioning device could be a flying head as is used in hard diskstorage devices. The stage 70 is located on an x, y, z, and θtranslation device 90. Alternately there are many known in the art asnano or micro positioning technologies. The laser light beam 110 is usedto form the image 27 of the micro discrete indicia 15 as shown in FIG.7.

[0031] Referring now to FIG. 6, there is illustrated yet anotherembodiment of the apparatus for forming the various indicia on agemstone using near-field optics made in accordance with the presentinvention. Indicia 15 are created on the gemstone 20 by transmittinglight from a laser 100. The laser light beam 110 is reflected by amirror 105, through a lens system 55 and passes through a taperedoptical fiber 115. The gemstone 20 resting on a stage 70 is placedwithin a critical distance f. The tapered optical fiber 115 ispositioned within a critical distance f; images formed from such asystem will have a lateral spatial resolution that exceeds the classicaldiffraction limit as is well known to those skilled in the art. Thetapered optical fiber 115 is positioned within the near-field couplinglimit appropriate for the particular tapered optical fiber in use by theuse of a positioning device 80. A method for the positioning of suchtapered optical fibers includes the measurement of mechanical dampingforces as a result of interaction of the fiber tip with the surface ofthe sample material. This interaction causes a shift of the mechanicalresonance frequency for the tip if it is vibrated upon approach towardsthe surface. As was previously described in FIG. 1, but is done onepoint at a time. Such a positioning device could be a flying head as isused in hard disk storage devices. The stage 70 is located on an x, y,z, and θ translation device 90. The laser light beam 110 is used to formthe image 27 of the micro discrete indicia 15 as shown in FIG. 4.

[0032] Referring now to FIGS. 7a and 7 b, there is illustrated a methodfor locating the micro discrete indicia 15 on the surface of thegemstone 20. For each producer of gemstones a unique set of thecoordinates (x₁, y₁) for the location of the micro discrete indicia 15can be specified. Using these coordinates the producer's unique microdiscrete indicia 15 can be located from a designated feature 128 such asa facet whose location is (x₀, y₀) or if polar coordinates are used is(r₀, θ₀). In another embodiment the coordinates (x₁, y₁) or (r₁, θ₁) forthe location of the micro discrete indicia 15 or can be specified on adocument of authenticity (not shown), which can accompany each gemstone20. The location (x₁, y₁) or (r₁, θ₁) of the indicia 15 can be givenfrom the designated feature 128 such as a facet whose location is (x₀,y₀) or if polar coordinates are used is (r₀, θ₀). In yet anotherembodiment of the present invention, the indicia 15 can be located byrepeatedly forming the indicia 15 using the near-field apparatus 10creating a set of indicia 125. The set of indicia 125 forms a markhaving a length “l” and height “s”, which is visible through a normaloptical microscope (not shown) and can be located using the normaloptical microscope. The length “l” and height “s” can be of a range ofbetween 0.02 millimeters to 0.1 millimeter depending on themagnification of the viewing microscope or viewing eye loop used. Afterthe set of indicia 125 has been located, the near-field opticalapparatus 200 (described in FIG. 8) is used to read the individual microdiscrete indicia 15, which by itself is not readable unless view throughthe near-field apparatus 200.

[0033] Once it has been determined that indicia 15 is present, referringnow to FIG. 8, there is illustrated the apparatus 200 for locating andviewing the indicia 15 formed on the gemstone 20. The indicia 15 on thegemstone 20 can be viewed using magnifying imaging device 200 or used tocapture an image of the indicia 15. A light beam 202 from a light source204 reflects from a beam splitter 206 and passes through an objectivelens 208 of conventional design and impinges onto a solid immersion lens(SIL) 210. The gemstone 20 resting on a stage 212 is placed within acritical distance f. The SIL 210 is positioned within the near-fieldcoupling limit appropriate for the particular lens in use by the use ofa positioning device 220. Such a positioning device could be a flyinghead as is used in hard disk storage devices. The light beam 202 isreflected from the gemstone 20, passes through the SIL 210, theobjective lens 208, and the beam splitter 206, imaging the indicia 15onto a sensor 226 by a lens system 224. The stage 212 is located on anx, y, z, and θ translation device 228. The x, y, z, and θ translationdevice 228 is and connected to the scanner 224 by a logic, control andmemory unit 230.

[0034] Referring now to FIG. 9, an enlarged partial view of the image232 of the indicia 15 captured by-the device 200 is shown. Using theimaging device 200, the image of the indicia 15 on the gemstone 20 isdisplayed for viewing for authentication and identification purposes.The size of the indicia 15 is such that the indicia 15 can appear on oneor more surfaces of the gemstone 20 as shown in FIGS. 2a, b, and c. Theindicia 15 formed on the gemstone 20 are of a size such that they arenot visually discemable on the gemstone 20 with the unaided eye undernormal viewing conditions or detract from the overall originalappearance of the gemstone 20. As previously discussed, the size ispreferably no greater than about 20 microns, and is generally in therange of about 2 to 20 microns. In situations where the micro discreteindicia is used for the purpose of personalization, ornamentation,decorative, or novelty the size of the micro discrete indicia may bemade as large as deemed appropriate. The size of the micro discreteindicia for personalization or ornamentation may be but is not limitedto a size range of 0.1 millimeters or larger. The size can be such thatit can be viewed by the user with an unaided eye or with the use of alow power loop.

[0035] The method comprises creation of the unique micro discreteindicia 15 using the apparatus 10 as described in FIG. 1. The uniquediscrete indicia 15 represents a unique identification number assignedor registered to an individual or business which directly links theindividual or business such as a retailer, producer, country of origin,or mine to the gemstone 20. The unique discrete indicia 15 are formed onthe gemstone 20 using near-field optics. The unique identificationnumber is then stored in a table as shown in Table 1 on a database andlinked with information such as carat, clarity, cut, color etcdescribing the gemstone, the information describing the owner, retailer,producer, country of origin, and/or mine along with the exact locationon the gemstone 20 of the micro discrete indicia 15. The location of themicro discrete indicia can be the given for a specific gemstone cut suchas a marquis, baguette, solitaire, etc. The location of the microdiscrete indicia can be also be designated by the owner, retailer,producer, country of origin, and/or mine as described in FIGS. 7a and 7b. To determine the authenticity of the gemstone 20 the uniqueidentification number is obtained by scanning the unique discreteindicia 15 on the gemstone 20 using the near-field optical imagingapparatus 200 as described in FIGS. 8 and 9. The unique identificationnumber is looked up on the table located in the database and theassociated information is retrieved. The owner, insurance company,retailer, law enforcement, producer, gem cutters and or mine can use theunique identification number and the database to identify a particulargemstone as to where the gemstone was mined, cut, who produced thegemstone, who sold the gemstone and who bought or owns the gemstone andto insure the gemstone is authentic. As can be seen from the foregoingthe providing of micro discrete indicia on gemstones made in accordancewith the present invention provides a method for allowing independentverification of the authenticity and/or the source of a gemstonedirectly from the gemstone, and also provides a mechanism forpersonalization, novelty, or decoration of such products. The inventionhas been described in detail with particular reference to certainpreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention. TABLE 1 ID Type of Country of Number Gemstone Origin ProducerCuter Retailer Owner Description Mine A12345678 Diamond Botswana DeBeersDiamond Patton's John Carat = 2 Fine Spoonhower Jewelry Debswana Factory12 First St. 34 Park Cut = Avenue Baguette Mining Company AmsterdamWebster, Rochester, NY Color E NY 14580 Clarity = VVS 8959R3652 EmeraldColumbia Gem Labs Gem Labs Patton's Juliana Carat = 1.07 Fine MeClainJewelry Coscuez 12 First St. 8 Central Park 7.0 × 5.0 mm Mines W.Emerald Cut Webster, New York, Strong NY 14580 NY Strongly Bluish GreenSlightly Included

[0036] It is to be understood that various changes and modificationsmade be made without departing from the scope of the present invention,the present invention being defined by the claims that follow.

[0037] Parts List

[0038]10 apparatus

[0039]15 unique micro discrete indicia

[0040]20 gemstone

[0041]25 mask

[0042]27 image

[0043]40 light beam

[0044]45 light source

[0045]50 mirror

[0046]55 lens system

[0047]65 solid immersion lens (SIL)

[0048]66 objective lens

[0049]70 stage

[0050]75 light beam

[0051]80 positioning device

[0052]90 translation device

[0053]100 laser

[0054]105 mirror

[0055]110 laser light beam

[0056]115 tapered optical fiber

[0057]125 set of indicia

[0058]128 facet

[0059]200 apparatus

[0060]202 light beam

[0061]204 light source

[0062]206 beam splitter

[0063]208 objective lens

[0064]210 solid immersion lens (SIL)

[0065]212 stage

[0066]224 lens system

[0067]226 sensor

[0068]228 translation device

[0069]230 logic and memory

[0070]232 image

What is claimed is:
 1. A gemstone having a micro-discrete indicia formedthereon wherein said micro-discrete indicia image was formed usingnear-field optics.
 2. A gemstone according to claim 2 wherein saidnear-field optics produces said micro-discrete indicia by ablation of animage on the surface of said gemstone.
 3. A gemstone according to claim2 wherein said micro-discrete indicia is produced using color centerproduction techniques.
 4. A method according to claim 2 wherein in saidmicro-discrete indicia is provided at a predetermined coordinates onsaid gemstone.
 5. A gemstone according to claim 2 wherein saidmicro-discrete indicia provides information with regard to saidgemstone.
 6. A method according to claim 5 wherein said informationcomprises any of the following: size, type, manufacturer, retailer,owner, producer, country of origin, mine etc.